Locomotive draft appliance



Nov. 4 1924. 1,513,832

I D. M. LEWIS LOCOMOTIVE DRAFT APPLIANCE Filed June 10 1919 5 Sheets-Sheet 1 -IIIIII l- I v M" I "a I I v I I l I x I l I I I I l I WITNESS Nov. 4 1924.

p. M. LEWIS LOCOMOTIVE DRAFT APPLIANCE Filed June 10 1919 3 Sheets-Sheet 3 Nov. 4 I924.

D. M. LEWIS LOCOMOTIVE DRAFT APPLIANCE Filed June 10 1919 3 Sheets-Sheet 5 Patented Nov. 4, 1924.

UNITED STATES PATENT OFFICE.

DAVID M. LEWIS, TOPEKA, KANSAS, ASSIGNOB OF TWO- THIRDS TO JOSEPH D. PURGELL, OF CHICAGO, ILLINO'IS.

LOGOMOTIVE DRAFT APPLIANCE.

Application filed June 10, 1919. Seriail No. 303,134.

.Be it known that I, DAVID M. Lewis, a citizen of the United States, residing at T0- peka, in the county of Shawnee and State of Kansas, have invented certain new and useful Improvements in Locomotive Draft Appliances, of which the following is a specification.

This invention relates to locomotive draft appliances and has for one of its primary objects the provision of an improved arrangement whereby the back pressure may be greatly reduced and the locomotive thereby rendered more efiicient.

Another of the important objects of my invention resides in the provision of means whereby the draft, and consequently the fire box conditions, may be modified by modifying 'or controlling the conditions in the exhaust passage or passages of the cylinders.

I furthermore provide an improved arrangement whereby I am enabled to carry off the exhaust steam more freely than has heretofore been possible.

Still another object of my invention is the provision of an improved draft appliance whereby I am; enabled to clean out the fire practically at will.

Finally my invention is directed to the provision of improved means whereby the back pressure conditions in the cylinder, or the pressure conditions in the draft appliance may be relieved without imparing the draft, and whereby I am enabled to conveniently and practically modify the draft appliance, from the cab or otherwise, to meet various different conditions that may arise from, the use of fuel of different characteristics and the like.

The foregoing, together with such other objects and advantages as may hereinafter appear, or are incident to my invention, I obtain by means of a construction, the preferred embodiment of which I have illustrated in the accompanying drawings, wherein Figure 1 is a longitudinal section through a smoke box to which my improvement has been applied; Figure 2 is an end elevation of Figure 1; Figure 3 is a view illustrating what may be termed a blower for the stack; Figure 4 illustrates a modified form of blower arrangement; and Figure 5 is a detailed view showing a modification of the invention.

My present improvements will be described in connection with a draft appliance of the type illustrated in the aforesaid pat-- ent and application.

Referring now to the drawings, the smoke box, or front end is indicated as a whole Vbv the reference letter AQthe flue sheet by reference letter B, the cylinders by letter C, the valve chests by letter D and the stack by letter E.

The stack E, which in the present embodiment, I have illustrated in association with a petticoat pipe 7, is of large volumetric capacity, preferably having an area approximating the total flue opening, for which purpose I prefer to construct the stack with a length approximating the width of the flue section giving the stack an elongated form with its major axis transverse of the smoke box. It will of course be understood that the petticoat pipe if used corresponds to the stack.

The nozzle F, is of the construction shown in co-pending application Serial No. 260,- 139, and in practice I construct it with length sufficient to properly cooperate with the stack to produce a draft substantially uniformly affecting approximately the full flue section. The nozzle orifice is of such character as to produce a draft of large volume and relatively low velocity and pressure, the size of the orifice being varied to, suit the particular type of engine to which the device may be applied or the particular service to which the engine is to be put. In

order to break up the pulsations of the exhaust, and to obtain substantial continuity of the draft, I provide the expansion chamber G to which the exhaust steam is conducted from the cylinders in a manner to be hereinafter pointed out, and from which the steam is conducted to the nozzle F through the passage 8 of the nozzle casting. The size of the expansion chamber will of course vary with the type of locomotive and l: tradistinction to the intermittent draft of standard practice with its low volume and high velocity. Furthermore, the draft effect is uniform over the entire flue section and also uniform over the fire box both trans versoly and longitudinally.

The foregoing method of drafting by large volume at low velocity, in addition to overcoming many of the difficulties and evils incident to the standard pulsating draft, greatly reduces backpressure, and increases the efficiency of the engine, but I have found, in addition, that the standard construction of exhaust passages was such that I was unable to conduct the steam to the expansion chamber as rapidly as the steam could be conducted therefrom to the stack and maintain the requisite draft. It fol- .lows, therefore, that if the steam can be conducted to the expansion chamber as rapidly as it can be pract-icably withdrawn there.- from for drafting purposes, that a still further reduction in back pressure may be obtained. Stated in other words the back pressure can be reduced to such a point as is necessary only to produce a draft of large volume and low velocity, and of approximate uniformity. I accomplish the desired results in the following manner:

I provide an exhaust passage, which in contradistinction to the exhaust'passages of standard practice is larger in cross sectional area and may be characterized by a capacity to carry off the steam at relatively low velocity and large volume. In the embodiment illustrated, the valve chamber is of the outside exhaust type and with this type, the exhaust passage means preferably takes the form of a pipe or pipes 9 bolted to the end or ends of each valve chest and leading to the expansion chamber. There but a single pipe 9 is used for each valve chamber, exhaust from the front end of the chamber takes place directly through the pipe, and exhaust from the rear end of the chamber takes place through the hollow spool of the valve. 'By this arrangement of piping I am enabled to increase the diameter of the pipe to a point where the area of the pipe will be as large or larger than the area of the exhaust ports. In addition, this arrangement provides a direct connection and it will be seen that for this reason as well as because of the increased size made possible, the exhaust pipes will carry the exhaust steam, at

relatively much lower velocity and larger volume, and they will, in effect, constitute a portion of the expansion chamber. In one sense of the Word therefore, it may be said that the exhaust steam opens directly to the expansion chamber in this arrangement.

The foregoing consideration has to do with back pressure conditions incident to construction, primarily. Back pressure conditions, both in the standard drafted engine as well as engines drafted in accordance with my invention, as materially affected by operating conditions, such for example as change in speed and cut-off of valves. In standard drafted engines, the back pressure rises with. the speed, assuming a normal operation of the cut-off, While apparently in a locomotive drafted in accordance with my improvements by a large volume relatively low velocity draft, which is substantially continuous, the back pressure is greatest at the lower speeds and drops off as the speed increases, probably owing to the fact that the engine, when working hard at low speed, and practically without expansion, utilizes larger volumes of steam than can be conveniently handled in the expansion chamber, as a result of which the pressure in the expansion chamber rises with a. consequent increase in back pressure in the cylinders. A material increase in expansion chamber pressure would alsomodify to some extent the draft produced. At high speeds, when the engine is using steam expansively less volumes of steam are exhausted into the expansion chamber, as a result of which the pressure therein is much lower and no back pressure difficulties are encountered.

I propose to overcome the back pnessure difficulties just above described, by controlling and regulating the conditions obtaining in the exhaust passages. In the application illustrated, this is accomplished by the provision of relief means, such for example, as the regulating valve 10. This Valve may be of the poppet type, the valve member proper being normally held to its seat by such means as a spring 11, suchspring having any predetermined value that may be selected. The valve 10 controls a discharge pipe 12 which is connected to the expansion chamber at any suitable point. It will be seen that the valve is subject to the pressure conditions obtaining in the expansion chamber, and when the pressure therein rises above the predetermined point at which the pressure of spring 11 is overcome, the valve will open and steam will discharge from the expansion chamber through pipe 12, as a re sult of which the pressure in the expansion chamber and the back pressure on the cylinders cannot rise above a predetermined selected value. Stated in other words the operation of the valve mechanism is equivalent to increasing the size of the nozzle orifice when the valve opens, or decreasing the nozzle orifice when the valve closes and thus it will be seen that by the use of the regulating valve all the advantages so long unsuccessfully sought in this art by the provision of variable nozzles constructed to alter the nozzle area, are obtained. The valve mechanism, therefore, acts as a back pressure regulator relieving the pressure on the exhaust side of the pistons when the operating conditions would otherwise have the normal tendency to increase such back pressure. It also acts to regulate the draft andmaintain it at a more constant value irrespective of saeed and other working conditions. Furthermore, the valve mechanism may be utilized as a convenient means for increasing or decreasing the draft as may be required to meet different service conditions, difierent fuels, and the like. By way of illustration, in the burning of lignite, a higher draft may be required and this also applies to certain classes of coal and fuel oil.

As one means for securing ready manual regulation of the valve mechanism, the valve may be provided with a piston or plunger member 13 against one face of which the spring 11 bears, the other face being subjected to air pressure, or the like, admitted through the pipe 14, leading back to the cab where it can be controlled by any suit able means. Upon the introduction of pressure through the pipe 14, the valve will be loaded in any desired amount, as a result of which higher pressures will obtain in the expansion chamber and a' discharge of higher velocity will occur through the orifice of the exhaust nozzle, thus increasing the draft.

From the foregoing it will be seen that I have provided a simple means for maintaining, within practical limit-s, at all operating speeds, approximate constancy in back pressure and approximate constancy at the nozzle; such means at the same time being capable of ready manipulation and adjustment so that a constant pressure of any desired value may be approximated.

I am also enabled by this arrangement to clean the fire, practically at will, for the valve may be loaded to such a degree that the pressures in the expansion chamber will temporarily rise to high values, thus temporarily greatly increasing the draft for fire cleaning purposes.

Furthermore, the arrangement is capable of use as a blower means, supplementing the nozzle, for which purpose, I prefer to have the pipe 12 discharged at some point stream line of the products of combustion, such ring being preferably provided with a plurality of upwardly directed outlet or discharge openings 16. The adaptation of the device as a blower is particularly adv'antageous, as in some instances, the valve 10 may deprive the expansion chamber of steam so rapidly as to cause a drop in the nozzle volume, resulting in too low a draft. This tendency would be overcome by leading the steam discharge from the pipe 12 to the stack, as described. In Fig. 4, the blower ring 15 is shown located around the nozzle.

An additional advantage incident to conducting the steam discharged from the expansion chamber through the pipe 12, to the interior of the stack, is that such discharge is almost in the form of water, which if discharged to the atmosphere, in cold weather, would be liable to lodge and freeze on the engine, and also obstruct the view of the engineer, whereas when discharged into the stack, it is subjected to the heated gases in a thin column or columns and is immediately reheated, discharging as more or less dry steam.

It is furthermore to be observed that when the steam abstracted from the expansion chamber is discharged into the stack, supplementing the nozzle, the discharge takes place at substantially the same pressure as the pressure at the nozzle, and therefore, the operation of the nozzle is not interfered with.

Under some conditions it may be desirable to vary the size of the expansion chamber. Thus for example, in starting up, with thethrottle only partly opened, and on long cut-off, the volume of steam delivered to the expansion chamber may be so small as to produce insufficient draft, as well as cause pulsations at the stack. Again at the high speeds, on short cut-offs, although the pulsatio-ns would not be present, or at best merely negligible, the pressure in the expansion chamber may be so low as to result in inefficient draft. In order to meet these conditions, I have provided a means for conveniently reducing the size of the expansion chamber, this means, in the embodiment shown, comprising a pair of butterfly valves 16, each mounted on a shaft 17 adapted to be operated from the cab. lVith this arrangement but a single stufiing box is required for each shaft. The valves are located at points to secure the desired amount of reduction in expansion chamber capacity.

If automatic control of the butterfly valves is desired, this can be readily accomplished by suitably connecting the valves as shown in Fig. 5 to a piston 18 which. is normally spring held in one position and is adapted to be subjected to the pressure in the pipe 12 on the discharge side of the valve 10. When the valve 10 is closed and there is no pressure operative on the piston or plunger 18, the butterfly valve will be held in closed position by the action of the spring 19 on the plunger, and when the regulating valve 10 opens, the pressure willmove the plunger 18 downwardly, thus opening the butterfly valves.

Since the natural stack draft may be too high when the engine is shut off, standing or running, or the engine is drifting, I provide the stack damper mechanism H, the blades of which are connected to a common operating member 20 connected to a piston 21 mounted in the chamber 22, the construction being such that the blades are normally gravity held in the closed position indicated in Figure 1. Opening into the bottom of the chamber 22 is a pressure pipe 23, to the lower end of which is fitted T 24 having oppositely acting check valves 25 and 26. A supply pipe 27 tapped into any source of live steam supply, as for example the steam space of a valve chamber, as illustrated in Figures 1 and 2, is connected to one branch of the T and a pipe 28 is connected to the other branch of the T, such latter pipe being connected to the blower 29 of the nozzle F. Steam is sup plied to the blower by means of the pipe 30 It will be seen therefore, that when the engineer opens the throttle, admitting live steam to the cylinders, live steam will enter pipe 27, pass the check valve 25 into pipe 23 and chamber 22, the pressure acting against the lower face of the plunger, raising the plunger and with it the member 20 which operates to open the blades of the damper. The. check valve 26 will be held in closed position. On the other hand if the engineer should operate the blower, blower pressure will enter the pipe 28, and pass the check valve 26. into the pipe 23, the operation thereafter being as just described. Insuch case the valve 25 will be held to its seat. It will be noted that the stack is enlarged at the top so that when the blades of the damper are in full open position they will occupy a position out of the stream line of the exhaust.

In order to drain the expansion chamber of water of condensation, I provide a discharge pipe 32 controlled by a valve mechanism 33, normally held in closed position. The drain valve is opened by admitting pressure to the valve chamber by means of pipe 34, to which air or steam may be supplied either from the pipe 35 leading to the cab, or by the pipe 36 coupled to the automatic drain cock mechanism of the cylinders. The drain cocks are diagrammatically illustrated at 37, and when pressure is supplied through pipe 88 to operate the same, it will also operate the drain valves 33.

I claim:

1. In a locomotive draft appliance, the

combination of an exhaust steam expansion chamber, means for conducting exhaust steam thereto, means for conducting steam therefrom, and means for cutting off a portion of the expansion chamber to reduce the space for expansion. 1

2. In a locomotive draft appliance, the combination of an expansion chamber, means for conducting exhaust steam thereto, means for conducting steam therefrom,

and valve mechanism for shutting off a portion of said chamber.

3. In a locomotive draft appliance, the

combinationof an expansion chamber,

means for conducting exhaust steam to the expansion chamber, and pressure controlled means for automatically cutting off a portion of the expansion chamber to reduce the space for expansion.

4:. In a locomotive draft appliance, the combination of an expansion chamber, means for conducting the exhaust steam to said chamber, and means for controlling the pressure conditions within the expansion chamber and utilizing the excess pressure for draft.

5. In a locomotive draft appliance, the

combination of an expansion chamber,

7 In a locomotivedraft appliance the combination of a nozzle, and means for conducting exhaust steam from the cylinders thereto, said means comprising a pipe bolted to the valve chest and opening directly from the exhaust space therein.

8. In a locomotive draft appliance the combination of. an expansion chamber,

a nozzle, means for discharging steam from the expansion chamber to the nozzle, and means for conduct ng exhaust steam from the cylinders to the expansion chamber,

said means comprising a pipe coupled to the valve chamber and opening directly from the exhaust space thereof.

9. In a locomotive draft appliance, the combination of an expansion chamber, means for conducting exhaust steam thereto, means for exhausting steam therefrom,

5 and means for discharging condensation from the expansion chamber, said means being pressure operated.

10. In a locomotive draft appliance, the combination of an expansion chamber,

10 means for conducting the exhaust steam thereto, means discharging steam therefrom, and means for discharging condensation from the expansion chamber, together With means whereby the operating of said discharge means may be manually controlled.

In testimony whereof, I have hereunto signed my name.

DAVID M. LEWIS. 

